Outdoor navigation and positioning has been widely deployed following the development of various global navigation-satellite-systems (GNSS) as well as various cellular systems. Indoor navigation and positioning differs from outdoor navigation and positioning because the indoor environment does not enable the reception of location signals from satellites or cellular base stations as accurately as in the outdoor environment. As a result, accurate and real-time indoor navigation and positioning are difficult to achieve.
Conventional indoor navigation and positioning methods, i.e. “fingerprinting”, “site-mapping” etc., calculate location by measuring received signal strength from an Access Point (AP). A handheld device initiates a location calculation by measuring the strength of a received signal and determines its position by figuring its distance from the location of a router or other access point transmitting the received signal. Unfortunately, these methods are inaccurate due to large variances in received signal strength. Fluctuations in received signal strength produce an approximately 20 meter radius of error. Another drawback of conventional indoor location methods is the inability of the network to initiate and significantly control the timing and management for location of a handheld device. When a device tries to query the location of APs in its vicinity, one query would preferably produce not only the location of a single AP, but also the location of that AP's neighbor APs as well. Receiving a complete tile, rather than the location of a single AP, reduces device power consumption and unnecessary air interface. In a managed network this is a solved problem because there is a centric data base containing the positions of the entire infrastructure in the venue. An unmanaged network presents challenges because an AP is not aware of the location of its neighbor APs in an unmanaged network.
In order for an unmanaged network to control the timing and management for location of handheld devices, the network must have the ability to discover the location of other access points belonging to the network that are in communication with the devices. Thus, there is a need for accurate indoor navigation and positioning methods that can be initiated and controlled by a network having known access points.